Although everyone tried his or her best to find solutions ,the problem remained_________

分类: 作业答案 • 2022-01-09 18:05:39

问题描述：

Although everyone tried his or her best to find solutions ,the problem remained_________
A to solve B unsolving C unsolved D solving

答

C.
如果要用solve.那么就要写成 tobesolved.
所以排除AD.
这里remain是做“一直保持”、“仍然（处于某种状态）”的意思,
所以后面要接一个形容词,C符合.